Move Selected Item Up or Down in PowerShell Listbox

Listbox Move Up Down Buttons.ps1 shows the event handlers for moving a selected item up and down in a PowerShell listbox. I wrote it because couldn’t find it anywhere else.

$handler_DownButton_Click= 
{
#only if the last item isn't the current one
   if(($ListBox1.SelectedIndex -ne -1)   -and   ($ListBox1.SelectedIndex -lt $ListBox1.Items.Count - 1)    )   {
        $listbox1.BeginUpdate()
        #Get starting position 
        $pos = $Listbox1.selectedIndex
        # add a duplicate of item below in the listbox
        $ListBox1.items.insert($pos,$listbox1.Items.Item($pos +1))
        # delete the old occurrence of this item
        $ListBox1.Items.RemoveAt($pos +2 )
        # move to current item
        $ListBox1.SelectedIndex = ($pos +1)
        $ListBox1.EndUpdate()
   }ELSE{
       #Bottom of list, beep
       [console]::beep(500,100)
   }
}

$handler_UpButton_Click= 
{
 # only if the first item isn't the current one
    if($ListBox1.SelectedIndex -gt 0)
    {
        $listbox1.BeginUpdate()
        #Get starting position
        $pos = $Listbox1.selectedIndex
        # add a duplicate of original item up in the listbox
        $ListBox1.items.insert($pos -1,$listbox1.Items.Item($pos))
        # make it the current item
        $ListBox1.SelectedIndex = ($pos -1)
        # delete the old occurrence of this item
        $ListBox1.Items.RemoveAt($pos +1)
        $ListBox1.EndUpdate()
    }ELSE{
       #Top of list, beep
       [console]::beep(500,100)
   }
}

Some things to note. I have error handling for moving too far up or down. The error is a beep using the [console] accelerator. BeginUpdate turns off the display while making changes to the listbox. EndUpdate turns them back on.